Inside caliper



March Z1, 1944. R. L. TARKET INSIDE GALIPER Filed May 24, 194s itil l 4 Patented Mar. 21, 1944 UNITED STATES PATENT OFFICE 1 Claim.

Other objects of the invention are to providev an inside caliper of the character described which will be comparatively simple in construction, strong, durable, highly efficient and reliable in use, compact and which may be manufactured at low cost.

A11 of the foregoing and still further objects and advantages of the invention will become apparent from a study of the following specification, taken in connection with the accompanying drawing wherein like characters of reference designate corresponding parts throughout the several views, and wherein:

Figure 1 is an elevational view of an inside caliper constructed in accordance with the present invention.

Figure 2 is an elevational View of the instrument, taken at right angles to Figure 1.

Figure 3 is a vertical sectional View, taken substantially on the line 3 3 of Figure 1, showing the contact points or lingers in open position.

Referring now to the drawing in detail, it will be seen that the embodiment of the invention which has been illustrated comprises a barrel I of suitable metal, said barrel including a knurled portion 2. One end portion of the barrel I has formed therein a longitudinal slot 3 providing bifurcations 4.

A rod 5 is mounted for longitudinal adjustment in the barrel I. Fixed on one end portion of the rod 5 is an elongated head Ii. One end portion of the head 6 is bifurcated, as at 'I. Contact points o r fingers 8 have one end pivotally secured by a pin 9 between the bifurcations 'I of the head 6. The slot 3 in the barrel I accommodates the contact points or lingers 8. The pivoted end portions of the contact points or fingers 8 have formed diagonally therein cam slots I0. A pin Il extending between the bifurcations 4 is engaged in the slots Ill. Thus, when the head 6 is adjusted longitudinally in the barrel I, the contact points or fingers 8 are caused to open or close.

Threaded on the other end portion of the rod 5 is a knurled adjusting knob I2. The adjusting knob I2 includes a smooth, reduced end portion I3 which is rotatable in the barrel I, said reduced portion providing a shoulder I4 for abutting engagement with the opposed end of said barrel.

Adjacent the inner end of the adjusting knob I2, a bushing I5 is mounted in the barrel I. The rod 5 is slidable through the bushing I5. Fixed on the rod 5 at a point in spaced relation to the bushing l5 is a collar I6. A coil spring I'I has one end engaged with the bushing I5 and its other end engaged with the collar I6 for yieldingly urging the rod 5 in a direction to open the contact points or ngers 8.

It is thought that the operation of the instrument will be readily apparent from a consideration of the foregoing. Briey, the device is inserted in the work and the adjusting knob I2 is turned in a direction to move the rod 5 toward the contact fingers 8 under the influence of the coil spring I'I. In this manner the ngers 8 are opened into engagement with the work. This is accomplished through the medium of the pin Il in the cam slots I0 causing the fingers 8 to swing on the pivot 9.

Of course, to swing the contact fingers 8 toward closed position, the adjusting knob I2 is turned in the opposite direction.

It is believed that the many advantages of an inside caliper constructed in accordance with the present invention will be readily understood and although a preferred embodiment of the instrument is as illustrated and described, it is to be understood that changes in the details of construction may be resorted to which will fall within the scope of the invention as claimed.

Having described the invention, what is claimed as new is:

An inside caliper comprising a barrel, a rod mounted for longitudinal adjustment in the barrel, contact ngers pivotally mounted on one end of the rcd, coacting means on the barrel and the iingers for opening and closing the latter upon adjustment of the rod in the barrel, a bushing mounted in the barrel at an intermediate point, the rod extending slidably through said bushing, a collar xed on the rod in spaced relation to the bushing, a coil spring in the barrel engaged with the bushing and the collar for yieldingly urging the rod in a direction to open the contact fingers, and an adjustment knob threadedly mounted on the other end portion of the rod, said adjusting knob including a reduced portion operable in the barrel and further including a shoulder for abutting engagement with the adjacent end of the barrel.

ROY LLOYD TARKET. 

